Turbine rotor cooling



May 22, 1951 Filed Aug. 23, 1944 W. A. LEDWITH TURBINE ROTOR COOLING UND01 2 Sheets-Sheet 1 FIG.

INVENTOR May 22, 1951 w. A. LEDWITH TURBINE ROTOR COOLING 2 Sheets-Sheet2 Filed Aug. 23, 1944 m: om.

mm mm \vm mm N0 m0 #9 ww INVENTOR Patented May 2 2, 1 951 TURBINE ROTORCOOLING Walter A. Ledwith, Hartford, Conn., assignor to United AircraftCorporation, East Hartford, Conn., a corporation of Delaware ApplicationAugust 23, 1944, Serial No. 550,887

9 Claims.

This invention relates to internally cooling the rotor of a turbine.

Cooling chambers have been placed in turbine rotors adjacent to thesupporting bearings to limit heat transfer to the bearings. Since oneend of the turbine rotor is generally connected to the mechanism drivenby the turbine, circulation of cooling fluid into the turbine rotor atthis end is diflicult. If the coolant is pumped into the rotor throughcollector rings an extremely high pressure is required to force thecoolant into the rotor against the centrifugal force resulting from thehigh rotational speed. An object of this invention is to overcome theseobjections by circulating the coolant through chambers adjacent bothends of the turbine rotor from a single coolant inlet at one end of therotor.

In turbines driven by hot gases, circulation of coolant through thepower section of the rotor has been avoided because the high temperatureof the power section may produce undesirable changes in the coolant. Afeature of this invention resides in directing coolant through the powersection of the rotor without direct contact with its hottest parts.

A feaure of this invention is the proportioning of the coolant betweenthe chambers in the rotor to assure adequate cooling in both chambers.

Another feature is the circulation of coolant through substantially theentire length of the turbine rotor so that coolant admitted at one endwill circulate through a chamber adjacent the other end.

Other objects and advantages will be apparent from the specification andclaims and from the accompanying drawing which illustrates an embodimentof the invention.

Fig. 1 is a sectional view through the turbine.

Fig. 2 is a sectional view on a larger scale through the central part ofthe turbine rotor.

The turbine shown includes a casing built up of rings I2, I 6, l6 and [8supported by radial pins 29 in a housing 22. These pins which are all insubstantially the same plane and which constitute the support for thecasing within the housing engage bores at bosses 24 in one ring it ofthe casing. Rotor 26 within the casing has a number of rows of blades 28alternating with the rows of nozzles 30 in the casing.

Housing 22 has a head 34 which forms a part of the housing and supportsa bearing sleeve 36 for the front end of rotor 26. At the other end ofthe turbine, the housing 22 supports a mounting 38 within which is abearing 4i! of the shaft. The mounting has a number of legs 42 engagingradial pins 44 in the housing.

Rotor 26 is made up of a number of discs 46, 48, 5E8 and 52, each ofwhich is substantially a constant stress disc, and shaft forming endelements 54 and 56. The discs and the end elements are all held togetherby a central bolt 58. The ends of the bolt are positioned within the endelements 54 and 56 and are connected to the end elements by threadedrings 60 and 62. Each of the rings 60 and 62 has inner and outer threadsengaging respectively with coopcrating threads on the bolt and on theend elements. On one of the rings the inner and outer threads may differin pitch so that as the ring is screwed into place, a substantialtension may be applied to the bolt.

Since the casing is built up of casing rings bolted together and sincethe rotor is built up of discs, it is apparent that the turbine isadapted for endwise assembly. To assist in aligning the discs, each discmay have projecting annular flanges on opposite sides havinginterengaging elements preferably in the form of face splinescooperating with similar elements on the adjoining disc. Similarly, theinner ends of the shaft elements 54 and 56 may have face splinescooperating with splineson the end discs.

Gas enters the first stage nozzles of the turbine through an inletscroll ill which is bolted on or otherwise attached to the end of casingIii. Gas from the turbine discharges through a duct 12 connected to theend casing ring and surrounding the rear bearing mounting.

Coolant is admitted to the rearward end of the rotor through a tube 14mounted in one of the projecting legs 42 of the bearing mounting 38 andconnecting with a passage 56 in bearing 40. A cap 18 on the bearingmounting has a connecting passage by which coolant from passage 16 isguided to a tube 82 extending through a cap 84 on the .end of thecentral bolt. Coolant enters at the axis of the rotor and does not haveto be pumped against centrifugal forces.

The bolt has radial passages $6 adjacent its rearward end whichcommunicate with a chamber 88 within the rotor permitting coolant toflow through this chamber and discharge through one or more grooves 98in the end element 56. Similarly, at the forward end of the bolt radialpassages 92 permit coolant to flow through a chamber 94 Within the endelement passage in the rotor packing I04 in end element 56 may be heldin.

place by sleeves I05 and I98 which'may be"integral with sleeves 60 and62. respectively. These sleeves have passages :I'lfi and H2 toipermit aflow of coolant from inside to outside :of the sleeve.

In order that the coolant as it'passes through the power section of theturbine rotor {shall snot be overheated a tube I I4 is placed within thehollow bolt and is held in spaced relation to the inner surface of thebolt by projectingribs l-IB on the tube. At opposite ends of the tubethe joint between the tube and bolt is made tight by seals or packing H8which may be held in place by rings [28 on the ends of the tube. Thispacking assists in holding the tube in spaced relation to the bolt. Apart of the coolant entering the rearward end of the turbine rotor flowsthrough the tube to reach the passages 92 at the forward end of therotor. is smaller than the inlet tube 82 to provide for The dimension ofpassage 86 .proportioning the distribution of the coolant between thetwo cooling chambers. It will be understood that the tube may be omittedif .it .is found that the bolt does not become too hot during turbineoperation.

Although the invention has been described in connection with a built-upturbine rotor it is applicable as well to a solid rotor of the typeshown in the co-pending application of Ledwith,

Serial No. 486,620, filed May 11, 1943, now Patent No. 2,415,104. Theturbine rotor in either event constitutes a rotating shaft, access toone end of which is diflicult. Coolant is circulated through I a chamberadjacent one end of the shaft or rotor by causing it to flow through anaxial passage in the rotor from the opposite end to which coolant maybeadmitted centrally of the shaft axis.

It is 'to be understood that the invention is ,not limited to thespecific embodiment herein illustrated and described, but may be used inother ways without departure from its spirit as defined by the followingclaims.

I claim:

1. In a turbine, a rotor having a power section with at least one row ofblades extending therefrom, axially spaced chambers adjacent oppositeends of the rotors, and lmeans for directing fluid to all of thechambers from one end of the rotor, said means including an axialextending through the power section and interconnecting the chambers,

a conduit for the fluid within and spaced from the walls of said passageand interconnecting the chambers, and sealing means around the conduitto keep the fluid out of the space surrounding the conduit.

2. In a turbine, a rotor having a power section with at least one row ofblades, spaced chambers located at opposite ends of the rotor, spacedbearings for the rotor located adjacent to said chambers, and means fordirecting fluid to both of the chambers from one end of the rotor, saidmeans including an axial passage in the rotor extending through thepower section and interconnecting the chambers, a conduit for the fluidWithin and spaced from the walls of said passage and interconnecting thechambers, and sealing means around the conduit to keep the fluid out ofthe space surrounding the conduit.

3. In -a turbine, a rotor having a power section with at least one row.of blades and a shaft extension at each end of the power section, eachshaft extension having a chamber therein, a bearing surrounding eachshaft extension and located adjacent to the chamber in each of said"shaftextensionsgmeans for directing coolant to .bothichambers :from oneend of the rotor, said means "including .a passage in said rotorextending between and interconnecting said chambers, and "a conduitwithin and spaced from the walls of the passage and through which thecoolant flows out of contact with the walls of the passage, and passagesextending through each shaft extension and communicating with theadjacent chamber through which the coolant in the chambers may bedischarged from the rotor.

4. .In a turbine, a rotor having a power section with at least one rowof blades and a shaft extension at. each end of .the power section, eachshaft extension having a chamber therein, a bearing surrounding eachshaft extension and located adjacent to the chamber in each of saidshaft extensions, means for directing coolant -to both chambers from oneend of the rotor, said means including a passage in said .rotorextending between and interconnecting said chambers, a conduit withinand spaced from the walls of the passage between the chambers throughwhich the coolant flows, and sealing means around the conduit to keepthe fluid out of the spacesurrounding the conduit.

5. In a turbine, a .rotor having .a power section and a shaft extension.at each end-of the power section, each shaft extension having a chambertherein, a bearing adjacent each chamher and surrounding each shaftextension, means for directing coolant to one of the chambers throughthe adjacent end of the rotor, a passage in said rotor connecting thechambers and a conduit within and spaced from 'the walls of the passagefor flow of coolant from said one chamber to the other chamber withoutcontacting the passage walls, and passages in the rotor adjacent eachend and communicating with each of said chambers for the escape ofcoolant therefrom.

6. In a shaft, a chamber adjacent one rendfa passage from said chamberto the other end of the shaft, means for directing fluid through saidpassage to said chamber, said means including a tube within and spacedfrom the walls of the passage, sealing .means around the tube to keepfluid out of the space surrounding the tube, and a discharge passageextending radially of the shaft adjacent to said chamber for the escapeof fluid.

7. In a shaft, a chamber adjacent one end, a passage from said chamberto. the other end of the shaft, a bearing surrounding said shaftadjacent to the chamber, and .means for directing fluid from said otherend of the shaft to .said chamber including a tube within and spacedfrom the walls of the passage, sealing means around the tube to keepfluid out of the space surrounding the tube, and a discharge passageextending radially of the shaft adjacent to said chamber for the escapeof fluid.

8. In a turbine rotor, a chamber adjacent one end, a passage throughsaid rotor from said chamber to the other end, a bearing surroundingsaid rotor adjacent to said chamber, and means for directing coolant tosaid chamber from said other end of the rotor, said means including atube within and spaced from the walls of the passage and extending fromsaid chamher to said other end of the rotor, sealing means around thetube to keep fluid out of the space surrounding the tube, and adischarge passage extending radially of the rotor adjacent to saidchamber for the escape of fluid.

9. In a turbine rotor, chamber adjacent one end, a passage through saidrotor fromsaid chamber to the other end, a bearing surrounding saidrotor adjacent to said chamber, and means for directing coolant to saidchamber from said other end of the rotor, said means including a tubewithin and spaced from the walls of the passage and extending from saidchamber to said other end of the rotor, sealing means around the tube tokeep fluid out of the space surrounding the tube, said tube taperingtoward said one end of the rotor, and a discharge passage extendingradially of the rotor adjacent to said chamber for the escape of fluid.

WALTER A. LEDWITH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,421,087 Johnson June 27, 19221,653,217 Koch Dem-'20, 1927 10 1,820,725 Bailey Aug. 25', 19311,828,782 Morton Oct. 27, 1931 1,938,688 Brook Dec. 12, 1933 2,073,605Belluzo Mar. 16, 1937 2,241,782 Jendrassik May 13', 1941 2,339,779Holzwarth Jan. 25, 1944 2,369,795 Planiol Feb. 20, 1945 2,461,239Schuster Feb. 8, 1949 FOREIGN PATENTS 20 Number Country Date 381,899Great Britain Oct. 13, 1932 506,479 Great Britain May 30, 1939 567,576Germany Jan. 5, 1933

